Pilot for valve grinding tools



June 15, 1937. H. w. znMMl-:RMAN

PILOT FOR VALVE GRINDING TOOLS Filed Dec. l5, 1934 Patented June 15, 1937 UNITED STATES PATENT OFFICE PILOT FR VALVE GRINDING TOOLS Application December 15, 1934, Serial No. 757,591

2 Claims.

'I'his invention relates to valve grinding tools,

and it has to do more particularly with a pilot for tools of this character which is adapted to be mounted within the usual valve guide for the 5 purpose of supporting and centering a grinding member with respect to the valve seat.

One of the objects of this invention is to provide an improved pilot of the foregoing character. Another object is to provide an improved pilot of simple construction which is inexpensive to manufacture, which serves the piloting function in a highly eiiicient manner, and which is of a character adapted to be easily, quickly, and firmly secured in the valve guide in proper centered re- 'A further object is to provide a punt of the foregoing character having a minimum number of parts and which is so constructed and arranged..l

that it is self-adjustable to the valve guide with- 0 out the manipulation of any parts whereby it automatically assumes the proper coaxial relation with respect to the valve guide regardless of the condition of the valve guide due to wear or the like. A more specific object is to provide a pilot 2 including, as an integral part thereof an attachment means including a group of annularly arranged fingers having their outer surfaces flared outwardly at their mid-portions to a diameter 0 greater than the diameter of the valve guide to provide a resilient and substantially line-contacting surface that engages the lower part of the valve guide, and which cooperatively with a tapered seat adjacent the other end of the pilot serves to properly set the pilot in proper coaxial relation with respect to the valve guide in which it is mounted. This feature of the invention serves to adapt tools of the foregoing character to a wide range of valve guide sizes, and it insures 40 proper relating of the pilot to the several valve guides of the same engine or of different engines, notwithstanding wear in such guides, whether the wear be uniform or of different extent.

Still another object is to provide means for 45 cushioning the ilexing action of the spring fingers guide (rather than the original axis thereof) so that the valve will be ground in proper centered relation with respect to the worn valve guide; to provide a universally adaptable tool that is selfadjusting with respect to each valve guide within its size range in a substantially uniform manner; and to provide a substantially one-piece structure which may be readily used by unskilledflabor with accurate results.

Other objects and advantages will become apparent as this description progresses and by reference to the drawing, wherein,-

Figure 1 is an elevational view, partially in section, of one form of structure embodying this invention, the same being shown in an operative relation with respect to a valve seat, valve guide and grinding member;

, Fig. 2 is a separated elevational view of the Ipilot shown in Fig. 1;

Fig. 3 is an enlarged sectional view of the lower end of the pilot of Fig. 2; and

Fig. 4 is a bottom plan view of the structure shown in Fig. 3.

The pilot illustrated in the drawing is well suited for use in connection with the grinding of a valve seat ID in an engine block II having a valve guide I2 which normally receives the stem (not shown) of a valve (not shown) adapted to cooperate with the seat I0.

In the grinding of the valve seat Ill, the pilot I3, with which my invention is particularly concerned, is mounted in the valve guideway I4 in centered relation with respect to the axis of the guideway. A valve seat grinding head I5 having a properly angled grinding surface I6 is rotatably mounted upon the upper or outer end of the pilot in any suitable manner.

by a tubular stem member I1 which finds rotatable bearing upon the upper end of the pilot I3, which member II may be driven through a shaft I8, which may be iiexible, if desired. It will be understood that the form of the grinding head and its support may take any suitable form, since a pilot embodying this invention is adaptable to various forms of grinders wherein the pilot is rigidly held within the valve guideway and the grinder rotates with respect thereto.

In the use of tools ofv this character for service work, it is desirable where the valve stem guide is not first reamed to oversize, to set the pilot coaxially with the valve guideway, even if the latter be worn, so that the valve seat will be ground with respect thereto. More particularly, in the normal operation of a valve like that hereinabove As shown in the drawing (Fig. 1) the grinding head I5 may be carried mentioned, the valve stem is usually operated by a cam-actuated tappet. In most cases, a cam strikes the tappet in such a way as to apply a side thrust thereto which, in turn, tends to wear the tappet bearing at an angle or in the direction of the thrust. The tappet is not directly connected to the valve stem, but this thrust is necessarily transmitted to the valve stem whereby the valve guideway is worn in a like manner. As this wear takes place, the valve stem naturally tends to adjust itself to a new axis so that the valve seat tends to wear more on one side than on the other. If the valve seat is to be ground without initially reaming the same to oversize, as is done in many normal repair jobs, it is desirable that the worn relationship between the valve guideway and the valve seat be maintained. The pilot structure embodying my invention, which will now be described, serves the foregoing purpose in a highly accurate manner by merely inserting the pilot axially within the valve guide.

The pilot I3 includes a4 body circular in crosssection and having an upper cylindrical shank portion I9 that is adapted to project above the engine block i i for rotatable support of the grinding member. At the lower end of the cylindrical pilot portion i9, there is provided a tapered seat 20, the lower end of which is adapted to readily enter the upper end of the valve guideway i4, the same gradually tapering outwardly to a diameter greater than that of the guideway, as best shown in Fig. 1. The lower end portion of the pilot is of tubular form being longitudinally split at 2i to provide a plurality (preferably, but not necessarily, four) flexible fingers or segments 22. This tubular end portion of the pilot is of a double-truncated cone form providing the exterior surfaces of the ngers 22 with bulging midportions 23 of greater diameter than the diameter of the valve guide to which the pilot is adapted. More particularly, the tubular finger portion is integrally connected to the tapered seat by a reduced stern portion 24. The tubular portion is so constructed and arranged (Figs. 2 and 3) that the outer surface thereof tapers outwardly from the stem portion 24 to a diameter at 23 normally greater than the diameter of the valve guideway I4, and then tapers inwardly to a diameter at 25 lesser than that of the valve guideway. In this way each finger 22 is similarly shaped toengage the valve guideway intermediate the ends of the finger in a substantially line contact manner. With this arrangement the pilot contacts the valve guideway only at the taper 20 and the bowed finger portions 23 when it is inserted in the guideway i4 (Fig. 1). This insures the proper centering of the pilot with the valve guideway notwithstanding the condition thereof, worn or otherwise. The fingers 22 are of such diameter at the point 23 that they are flexed inwardly when inserted in the valve guideway. The oversize of the finger contacting portions 23 is such that, when the pilot is fully inserted in the valve guideway, the tendency of such fingers to expand causes the same to firmly grip the valve guideway and securely hold the pilot in operative position therein. The shape of the lower tubular end portion of the pilot also provides the reduced end portion 25 which is adapted to readily enter the upper end of the valve guideway to facilitate application of the pilot to the latter.

In the use of a pilot of this character, it is desirable to provide a feel thereto when it is being inserted in or removed from the valve guideway. To that end I provide means for cushioning the inward exing action ofthe fingers 22. More particularly, I mount within the tubular portion defined by the fingersy 22 a resilient filler or block 26. Any material which will serve to provide the cushioning action may be employed, and I have found that a plug of comparatively soft and pliable rubber material well serves this purpose. Such a plug readily permits of the inward flexing of the fingers 22, and it also serves to avoid unintentional distortion of the fingers and to hold the same in their intended normal condition before insertion within the guideway. The plug 26 further serves to prevent dirt and the like from entering the space defined by the fingers 22.

In the form of structure shown in the drawing, the plug 26 does not extend entirely to the end of the ngers 22. This permits of added flexibility at the extreme end portion of the fingers to facilitate the insertion of the tool within the valve guideway. However, ii.' desired, good results may be obtained by using a plug which extends entirely to the ends of the fingers. It will also be understood that, if desired, the plug 26 may be omitted in certain cases. In that event, the normal resiliency of the fingers 22 is depended upon for such feel as may be desired.

It is believed that the manner of use of the pilot and its advantages will be readily understood from the foregoing description. I have found that a pilot constructed according to my invention well serves the intended purpose. While it may be readily inserted in and removed from the valve guldeway, its construction is such that it is held firmly and rigidly when in operative position within the valve guideway. This is accomplished. by a one-piece construction of self-adjusting character that may be fastened in place merely by inserting the same axially within the guideway. The shape of the lower end of the pilot, together with the taper 20, insures the desired positioning of the pilot along the proper axis for guiding the grinding member i5 in its rotation to properly grind both worn and unworn valve seats. 'I'he pilot will self-adjust itself to the proper coaxial relationship notwithstanding irregularities in the valve guideway surface. A pilot embodying this invention is adaptable for universal application within its size range with substantially uniform results in all cases.

It will be understood that, while a particular adaptation of this invention has been shown and described, various changes and modidcations may be made without departing from the spirit and scope of this invention as defined by the claims that follow.

I claim:

1. In a pilot oi.' the class described, a body member circular in cross section, and means for firmly securing said body member in a valve guide which includes a tubular portion at one end of the body that tapers outwardly from a point of lesser diameter than the valve guide to a point of greater diameter than the valve guide and then inwardly to a diameter of less than the diameter of the valve guide. said tubular portion being split longitudinally to provide an annular series of flexible ngers, the increased diameter portions of said fingers frictionally engaging the valve guide way with sufficient force -when inserted therein to self-hold the pilot rmly in place, and means resilient Within said tubular portion and extending from the inner end thereof toward but short of the outer ends of said ngers for resiliently opposing inward viiexible movement of said fingers and causing said ngers to ilex in a. substantially uniform manner from their inner to their outer ends.

2. A pilot for a valve seat grinder having a rotatable grinding member, which comprises an upper cylindrical part adapted to rotatably support the grinding member, and a lower part adapted to be inserted in a valve guide, said lower part including a reduced stem portion, an upwardly and outwardly arlng taper portion at the upper end of said reduced stem portion, and a tubular portion at the lower end of said stem portion, said tubular portion being split to provide an annular series of exible fingers, and said ngers having their mid-portions thickened and bulged outwardly to provide an external and substantially line contacting surface adapted to engage the valve guide way intermediate the ends of said ngers, and a plug inserted within said tubular portion, said plug being formed of a rubber material fitting snugly within said tubular portion and being of a length less than said lingers so that it extends from the inner ends of said ngers slightly past their midportions.

ERMAN W. I' l'sil MAN. 

